氮营养水平对烤烟根际土壤酶活性及烟叶内在品质的影响

Effects of Nitrogen Fertilizer on Tobacco Soil Enzyme Activities and Flue-cured Tobacco Immanent Quality

田间试验研究了不同时期烤烟根际各土层土壤酶活性变化规律及其不同施氮量对烟叶品质的影响。结果表明：0～20cm土层范围内，施氮可以提高圆顶期、采烤期及采烤结束后土壤脲酶、转化酶的活性，但当施氮量超过52．5kg hm^-2时，脲酶、转化酶的活性反而降低；土壤蛋白酶活性均在37．5kg hm^-2处理达到最大值，且随着施氮量的增多大都呈现降低的趋势。20—80cm土层范围内，土壤脲酶、转化酶、蛋白酶活性变化规律并不一致。对于烤后烟叶，施氮量为52．5kg hm^-2的烟叶，糖碱比、氮碱比、钾氯比均比较适宜，化学成分较为协调，燃烧性较好，有利于优质烟叶品质的形成。说明在该地区的试验条件下，水稻土种植烤烟最适宜的施氮量为52．5kg hm^-2。

The field experiment was conducted on planting tobacco soil to research variation rules of soil enzyme activities in different soil layers at different stages and to research the effects of different nitrogen levels on tobacco quality. The results showed that at 0 - 20 cm soil depth, the N application was helpful to increase the activities of soil urease, invertase. When the N applied was over 52.5 kg hm^-2, the activities of soil urease, invertase were decreased. The activities of soil protease reached its maximum when the N applied was 37.5 kg hm^-2, along with the N of going up, the activities of soil protease presented a trend of decreasing. At 20 - 80 cm soil depth, the variation laws of the activities of soil urease, invertase, protease were inconsistent. To the flue-cured tobacco, when the N applied was at 52.5 kg hm-2, the ratio of total sugar to nicotine, total nitrogen to nicotine and potassium to chlorine were more appropriate, the chemical composition tended to coordinate and burning performance was much better, and it had still helped to form excellent quality of flue-cured tobacco. It also indicated that 52.5 kg N per hectare was the most proper nitrogen in the paddy soil under the experimental condition.